As will be appreciated by those skilled in the art, specialized helical shaped devices such as screw conveyors are well known for the transport of various types of bulk material. Such conveyors generally include a helical shaped member which rotates within a housing or trough such that rotation of the screw conveyor along its longitudinal or central axis results in movement of the bulk material along the length of the device. In the past, such conveyors were typically constructed from metal, and each conveyor was specifically designed for a particular purpose and of a particular length. However, although most prior art conveyors were specifically designed to meet a particular appication, there have been some attempts of providing a modular type conveyor of metal and wood. Examples of U.S. Patents which disclose such modular conveyors include U.S. Pat. No. 349,233 issued to James Nelson on Sept. 10, 1886; U.S. Pat. No. 455,384 issued to H. Binkholz on July 7, 1891; U.S. Pat. No. 525,194 issued to J. Dyson, et al on Aug. 20, 1894; U.S. Pat. No. 546,879 issued to J. Dyson, et al on Sept. 14, 1895; U.S. Pat. No. 1,867,573 issued to D. G. Leach on July 19, 1932; U.S. Pat. No. 2,492,915 issued to A. B. Carlson on Dec. 27, 1949; U.S. Pat. No. 3,648,826 issued to Dean P. Brooks on Mar. 14, 1972 and U.S. Pat. No. 3,705,644 issued to Claude E. Kawchitch on Dec. 12, 1972. However, a study of the above patents indicates that only the two Dyson, et al patents, the Nelson patent and the Kawchitch patent can be considered sectional or modular. In additional, the assignee of the present application filed on application for Letters Patent on Sept. 29, 1983 for a "Modular Screw Conveyor" and which has Ser. No. 537,345, and on Apr. 4, 1984 filed an application for "Mold and Process for Manufacturing helical Shaped Items" which has Ser. No. 598,374.
As will be appreciated, one of the advantages of the plastic modular screw conveyor is its ease of cleaning, etc. due to the smooth and non-interrupted surfaces. Also of course, by axially stacking any selected number of modules on the non-circular drive shaft a screw conveyor of any length can be fabricated. Of course, even though a multiplicity of a single type module can be used to manufacture screw conveyors of almost any length, until the present invention, the drive shaft had to be "cut to length" for each different screw conveyor. The requirement of such a "tailored" drive shaft was expecially true for certain applications wherein a joint or interruption in the screw conveyor to allow for joining two sections of a drive shaft simply could not be tolerated. In addition, for certain U.S.D.A. applications the assemblage of individual modules must be sealed to each other at their end surfaces to eliminate any cavities etc. which might harbor bacteria. For such applications, a one piece drive shaft was absolutely necessary no matter how long the screw conveyor, since shaft couplings available at that time which used sleeves and bolts were unacceptable and would not provide the uninterrupted and crevice-free surfaces.
Therefore, it is an object of the present invention to provide a drive shaft coupling which can be used with a multiple module screw conveyor.
It is another object of the present invention to provide a drive shaft coupling which is completely enclosed and protected by the screw conveyor modules.
It is yet another object to provide a drive shaft coupling which is inexpensive and easy to assemble and disassemble.